LCMXO2-640ZE-3TG100C datasheet(12/106 Pages) LATTICE

12 / 106 page

2-8

Architecture

MachXO2 Family Data Sheet

The LOCK signal is asserted when the PLL determines it has achieved lock and de-asserted if a loss of lock is

detected. A block diagram of the PLL is shown in Figure 2-7.

The setup and hold times of the device can be improved by programming a phase shift into the CLKOS, CLKOS2,

and CLKOS3 output clocks which will advance or delay the output clock with reference to the CLKOP output clock.

This phase shift can be either programmed during configuration or can be adjusted dynamically. In dynamic mode,

the PLL may lose lock after a phase adjustment on the output used as the feedback source and not relock until the

tLOCK parameter has been satisfied.

The MachXO2 also has a feature that allows the user to select between two different reference clock sources

dynamically. This feature is implemented using the PLLREFCS primitive. The timing parameters for the PLL are

shown in the table.

The MachXO2 PLL contains a WISHBONE port feature that allows the PLL settings, including divider values, to be

dynamically changed from the user logic. When using this feature the EFB block must also be instantiated in the

design to allow access to the WISHBONE ports. Similar to the dynamic phase adjustment, when PLL settings are

updated through the WISHBONE port the PLL may lose lock and not relock until the tLOCK parameter has been sat-

isfied. The timing parameters for the PLL are shown in the table.

For more details on the PLL and the WISHBONE interface, see TN1199, MachXO2 sysCLOCK PLL Design and

Usage Guide.

Figure 2-7. PLL Diagram

CLKOP, CLKOS, CLKOS2, CLKOS3

REFCLK

Internal Feedback

FBKSEL

CLKOP

CLKOS

CLKOS2

CLKOS3

REFCLK

Divider

M (1 - 40)

LOCK

ENCLKOP, ENCLKOS, ENCLKOS2, ENCLKOS3

RST, RESETM, RESETC, RESETD

CLKFB

CLKI

Dynamic

Phase

Adjust

PHASESEL[1:0]

PHASEDIR

PHASESTEP

FBKCLK

Divider

N (1 - 40)

Fractional-N

Synthesizer

Phase detector,

VCO, and

loop filter.

CLKOS3

Divider

(1 - 128)

CLKOS2

Divider

(1 - 128)

Phase

Adjust

Phase

Adjust

Phase

Adjust/

Edge Trim

CLKOS

Divider

(1 - 128)

CLKOP

Divider

(1 - 128)

Lock

Detect

ClkEn

Synch

ClkEn

Synch

ClkEn

Synch

ClkEn

Synch

PLLDATO[7:0] , PLLACK

PLLCLK, PLLRST, PLLSTB, PLLWE, PLLDATI[7:0], PLLADDR[4:0]

Mux

DPHSRC

Phase

Adjust/

Edge Trim

STDBY

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